The overall goal of this revised research career award application is to provide the conceptual background and research skills necessary for Dr. Timothy W. Fong to conduct patient-oriented research in pathological gambling. Drs. Thomas Newton, Nancy Retry and Richard Rosenthal will provide expert training in clinical issues in pathological gambling and addictions research. With this award, Dr. Fong will obtain research skills through a project that examines the relationship of impulsivity to pathological gambling. Impulsivity has been described as the cognitive inability to delay gratification, a failure to inhibit behavioral action or acting without forethought about consequences. Impulsivity has also been seen as a personality trait characterized by risk-taking or sensation-seeking behavior. Pathological gamblers demonstrate aspects of impulsivity;they act without thinking, have difficulty-inhibiting urges to gamble and desire immediate gratification. The goal of this project is to clarify which components of impulsivity are associated with pathological gambling. Non-treatment seeking, pathological gamblers and controls will be recruited from the community. Each participant will be administered a battery of tests that represent different operational definitions of impulsivity. Personality traits of impulsivity will be performed with the Barratt Impulsiveness Scale and the Eyesenck Personality Questionnaire. Behavioral components of impulsivity will be tested through delay and probability discounting tasks. Finally, sensorimotor gating as measured through pre-pulse inhibition of acoustic startle will serve as a putative neurophysiological measure of impulsivity. Between group comparisons on this battery of impulsivity tests will be made to clarify which components of impulsivity are associated with pathological gambling. Secondly, within-group analyses will be performed to correlate impulsivity to gambling severity. Lastly, an exploratory analysis of sub typing pathological gamblers by performances on tasks of impulsivity and types of gambling will be conducted.